Mechanisms of Canopy Development of Tall Fescue Genotypes1
- C. J. Nelson,
- K. H. Asay and
- D. A. Sleper2
Little is known regarding the genetic control of yield components of forage grasses. We conducted four experiments to determine if genotypes of tall rescue (Festuca arundinacea Schreb.) differed in number of tillers and weight/tiller. The relationship between those traits and yield/plant was also investigated under low-competition conditions.
Genotypes selected for high number of tillers exhibited lower yield/tiller, and often a lower yield/plant than those with a low number of tillers, when cut following 18 to 24 days of regrowth. Among 225 plants from a 6Χ6 diallel series diallel series, tillers/plant was negatively correlated (r = —0.55) with yield/tiller. Path coefficient analyses revealed that the direct effect of tillers/plant on yield/plant was about 1.5 times greater than that of yield/tiller.
Rate of leaf area expansion was related closely to yield/tiller among genotypes that were selected to represent a broad range in number of tillers/plant. The relationship was not as close (r = 0.43) among progenies of the diallel. Path coefficient analysis of the diallel progeny indicated that leaf elongation rate had 1.6 to 1.8 times more influence than did leaf width on leaf area expansion rate. Leaf area expansion rate may be an acceptable criterion for selection for yield/tiller. Concentration of water-soluble carbohydrates in leaves and CO2 exchange rate of leaves were not related to number of tillers/plant, yield/tiller, or leaf area expansion rate.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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